Overexpression of <i>LtKNOX1</i> from <i>Lilium tsingtauense</i> in <i>Nicotiana benthamiana</i> affects the development of leaf morphology

Leaves are the main vegetative organs of the aboveground part of plants and play an important role in plant morphogenesis. <i>KNOTTED-LIKE HOMEOBOX</i> (<i>KNOX</i>) plays a crucial role in regulating leaf cell fate and maintaining leaf development. In this study, we analyzed <i>LtKNOX1</i> from <i>Lilium tsingtauense</i> and illustrated its function in transgenic plants. Tissue-specific expression analysis indicated that <i>LtKNOX1</i> was highly expressed in stems, young flower buds, and shoot apical meristems (SAMs). Ectopic overexpression of <i>LtKNOX1</i> in <i>Nicotiana benthamiana</i> suggested that transformants with mild phenotypes were characterized by foliar wrinkles and mildly curled leaves; transformants with intermediate phenotypes showed severely crimped blades and narrow leaf angles, and the most severe phenotypes lacked normal SAMs and leaves. Moreover, the expression levels of genes involved in the regulation of KNOX in transgenic plants were detected, including <i>ASYMMETRIC LEAVES1, PIN-FORMED 1, GA20-oxidase, CUP-SHAPED COTYLEDON 2, CLAVATA 1</i> and <i>WUSCHEL</i>(<i>WUS</i>), and the expression of other genes were down-regulated except <i>WUS</i>. This study contributes to our understanding of the <i>LtKNOX1</i> function.